For mobile terminals such as mobile phones, for example, input apparatuses used by a user to operate the terminals have been developed in various manners according to functions and usages of the terminals. In many cases, the input apparatuses are configured to allow a user to perform an input operation by directly pressing down mechanical keys or buttons prearranged on a surface of a body of the mobile terminal.
The mechanical keys (numerical keypads, for example) of the input apparatuses of the mobile terminals are typically prearranged according to a main usage of the terminals. In general, the physical arrangement of keys defined first cannot be rearranged afterward.
Incidentally, there recently are small mobile terminals with a variety of functions incorporated therein, such as the mobile phones having functions of a digital camera and of a music player installed therein. There are mobile terminals, such as the mobile phones, having numerous supplementary functions incorporated therein in addition to a function for a main usage, and PDAs (Personal Digital Assistant: mobile information terminal) having a plurality of main usages within respective terminals, such as schedule management, an address book and the like. For such terminals, the fixed arrangement of keys may cause inconvenience significantly in input operation using certain functions.
In order to resolve such inconvenience, there is disclosed an input apparatus having a touch panel in which a transparent input unit is arranged on a front face of a liquid crystal display panel, which is a display unit (for example, see Patent Document 1). The input apparatus having such a touch panel is generally configured to display graphical images of operation keys or buttons (hereinafter, referred to as “objects”) on a display screen of the touch panel. When the user presses an object displayed on the display screen, the input unit of the touch panel at a corresponding position receives an input.
Since the input apparatus having such a touch panel receives an input in the form of a user's direct contact (touch) to the object displayed on the display unit with a user's fingertip or the like, it allows the user to operate highly intuitively. That is, the user operates the input apparatus by directly touching the object displayed on the screen with the fingertip or the like following a guide displayed on the screen of the touch panel. Therefore, it allows the user to operate the terminal extremely easily by an intuitive operation following the guide displayed on the screen and, as a result, offers an effect to reduce incorrect operations.
As stated above, since the touch panels have advantages that allow for a freer configuration of the input units and enable highly intuitive input operations, the terminal apparatuses having the input units with the touch panels have been on the increase.
In order to further improve operability of such a touch panel, there is suggested an input apparatus provided with a pressure detection means for detecting an operation pressure on the touch panel and capable of receiving an input in accordance with pressure load of the input by a user (for example, see Patent Document 2). Accordingly, this input apparatus can be controlled not to receive an input unless the pressure applied to the touch panel is equal to or higher than a predetermined pressure. Therefore, this input apparatus can prevent erroneous operations, such as a reception of a mere contact to the touch panel.